تاثير حامض الاسكوربيك وانزيم الكلوكوز اوكسيديز في الصفات النوعية والريولوجية لدقيق الحنطة المحلية ضعيفة الكلوتين == Effect of ascorbic acid and glucose oxidase enzyme on the rheological properties and quality of the local wheat flour of weak gluten
Author name:
وسام كريم عبيد الربيعي
Supervisor name:
علي احمد الساهي
General topic:
Agricultural sciences
Specific topic:
Food
Degree:
Master
University:
University Of Basrah - Faculty Of Agriculture
Language:
Arabic
University location:
Basrah
First pages:
31T1885 - p.pdf
Abstract:
This study was carried out as an attempt to improve rheological and chemical properties of local wheat flour of weak gluten, by the addition of ascorbic acid and glucose oxidase enzyme as individuals and in synergy, to the flour.The chemical composition of local wheat flour and imported wheat was studied (Eba’e 99 , Rasheed , Bihooth , Australian) . Reduction of protein percentage was noticed of local wheat's varieties compared with protein percentage of imported wheat . The highest protien percentage was in imported wheat 13.55% and the lowest was in Eba’e 99 wheat 12.1% , at the same time ,the highest ash percentage was in Eba’e 99 wheat flour, 1.06%, whereas the highest percentage of fat was in Rasheed variety 1.8% . It was noticed the raise of dry and wet gluten in imported variety flour ,it reached 32.5 , 10.8% frequently. Whereas the results related to the tests of flour strength showed the surpass of imported class that the value of Pelshenke test 250 minutes, Zeleny test was 41 cm3, compared with local variety, Whereas Eba’e 99 variety showed the lowest values compared with studied classes, it reached the value of Pelshenke test 92 minutes, sedimentation test was 20 cm3.The flour used in the study was evaluated of rheological properties for Eba’e 99 wheat flour using farinograph and extensograph tests, to be not useful for bread making, It has Developing and stability times were low. It has a high degree of softening, farinograph quality number were low . Its extension resistance, extensibility and extensograph area were low as compared to those of normal bread flour.The flour (80% extraction) was treated by the addition of ascorbic acid and glucose oxidase as individuals and in synergy, in order to study their effects as improvers in the rheological properties of wheat flour dough. The results were as follows : 1. Ascorbic acid and glucose oxidase possessed a positive effect on the rheological properties when it were added them as improvers to the wheat flour as individuals with Different concentrations. The concentration of 50 ppm and 20 ppm respectively, were the best among different concentrations according to farinograph and extensograph tests.2. Synergetic effect of Ascorbic acid and glucose oxidase was observed highest readings of farinograph test, it reached the value of developing and stability times 5.0 , 4.3 minutes, respectively. It has low in degree of softening 63 FU, Whereas the farinograph quality number was raising to 59. Its extensograph readings were high, the recorded elastic recovery was 4.6, 4.0 and 4.2 at interval times (45, 90, 135) min, respectively.The results treatment of the flour with Ascorbic acid and glucose oxidase as individuals and in synergy showed significant and another non - significant increase in wet and dry gluten content and a significant increase in gluten index. The best results were obtained in the flour which had treated with Ascorbic acid and glucose oxidase as in synergy with concentrations of 40 ppm and 0.001%, respectively in which the gluten index reached 87.09%.A significant increase of disulfide concentration accompanied by a significant decrease in free sulfhydryl concentration were obtained by treating the flour with Ascorbic acid and glucose oxidase, especially with in synergy treatment by which disulfide concentration was significantly raised to 3.421× 10 - 4 mole/gm gluten as compared to control sample (3.101 mole/gm gluten). This effect caused improvement of dough properties especially in retaining of carbon dioxide gas in the gluten network. A significant decrease in loaf weight accompanied by a significant increase in both the volume and specific volume were obtained upon all treatments.The best result was obtained by treating the flour with Ascorbic acid and glucose oxidase, as in synergy with concentrations of 40 ppm and 0.001% .Sensory evaluation of the produced loaf, which was conducted by proficient in cereal chemistry and technology, showed a significant improvement in all of its quality parameters in the treated flour. The effect of Ascorbic acid and glucose oxidase, as in synergy was very clear in improving all of sensory parameters as compared to the untreated flour sample.
